SECURITY fears have led to Prime Minister Tony Abbott cancelling a planned trip to Geelong as students vow to take to the streets today in a protest touted as the biggest of its type in a decade.

Mr Abbott and Education Minister Christopher Pyne were due to attend the Deakin University campus for the official opening of its Carbon Nexus research facility but cancelled on advice from the Australian Federal Police.

Mr Pyne said the AFP expressed concerns about their safety and that of “innocent bystanders”.

“So the prime minister made the decision ... that it would be wiser to not go and to create that tumult,” Mr Pyne told ABC TV.

He criticised protesters for complaining about having to contribute more to their own education and accused them of seeking to shut down democracy.

He said people should be free to express their opinions without being “assaulted and molested”, as Foreign Minister Julie Bishop and former federal Liberal MP Sophie Mirabella had been by protesters at Sydney and Melbourne universities over the week.

Geelong Trades Hall Council secretary Tim Gooden said a number of protesters were still planning to be at the shopping centre opening, where they would peacefully voice their disgust at last week’s Federal Budget.

“He’s just kicked workers and poor people in the guts, so I think he’ll be doing whatever he can to avoid them in the next six months,” Mr Gooden said.

“This was a political decision not to come, he would have been perfectly safe. He just didn’t want the bad publicity.”

In Geelong, unions, students, pensioners and other protesters were planning to voice their disgust at last week’s Budget to the PM, who was scheduled to attend three events.

The PM’s office said security advisers were concerned by reports that thousands of activists were planning to show up, some coming by bus from Melbourne.

“Based in security advice, the Prime Minister unfortunately won’t be in attendance at Deakin University in Geelong,” a spokesman for Mr Abbott said last night.

Planned events included a private $500-per-head Liberal luncheon at The Lord Of The Isles Hotel, the public opening of the expanded Waurn Ponds shopping centre and the official invite-only opening at Deakin.

About 70 people were expected at the luncheon and up to 300 at the Deakin event.

Meanwhile, up to 1500 university students furious at higher education changes will today converge on Melbourne’s CBD in a rally touted as the biggest of its type in a decade.

The demonstration will form part of a national day of action against the changes.

But organisers vow there will be no repeat of ugly scenes from a similar event last year.

National Union of Students national president Deanna Taylor, whose group is organising the CBD rally with the National Tertiary Education Union, said students who didn’t typically protest were set to take part.

Trade unions were also likely to join the demonstration, to begin at the State Library at 2pm.

It will include a symbolic burning of the Budget.

“We haven’t had a rally of this magnitude and an issue of this magnitude for about 10 years,’’ Ms Taylor said.

The union did not condone violence “in any way shape or form” and wanted the demonstration to be peaceful, she said.

Tertiary union national president Jeannie Rea urged universities not to punish students who participated.

The Federal Government’s university changes would threaten the viability of some institutions and impose enormous costs on students, she said.

Universities will be able to decide how much they charge for degrees and students forced to repay government debts earlier as part of the higher education overhaul.

The amount of money the Commonwealth gives to universities for each course will also be cut.

Demonstrators in a similar rally clashed with police last October, putting one officer in hospital.

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